1. Field of the Invention
This invention relates to an apparatus and method for attaching cleats to belts, and more particularly, to an apparatus and method for heating cleats and belts to a fusing temperature and then rolling a wheel over the cleats.
2. Description of Related Art
It is known in the art to attach cleats to conveyor belts by heating portions of both the cleat and belt to a fusing temperature and employing a wheel or roller to press the heated cleat and belt together to fuse them. Cleats generally have a horizontal base with a stem extending upwardly therefrom. It is also known to provide a wheel which is slotted between its lateral sides to accommodate the stem portion of the cleat therein, with the perimeter of the wheel on either side of the slot pressing on the base portion of the cleat.
It is common for such cleat attachment to be done in batch-type operation, wherein cleats of different sizes, shapes and materials are attached in each batch run. Additionally, it is required to attach this variety of cleats both longitudinally, along the length of the belt, and transversely, across the width of the belt.
It was previously believed necessary to run the aforementioned variety of operations on separate machines with each machine designed to attach one particular type of cleat in one particular orientation. Or, in the alternative, a few of the various operations could be performed on a single machine, but only with extensive retooling between each type of operation.
Such transferring between machines and extensive retooling between each operation results in considerable undesired downtime. Thus, there is a need for a single machine capable of attaching various sizes and shapes of cleats to a conveyor belt, either longitudinally or transversely, with a minimum amount of adjustments and retooling between consecutive, varying operations.
It is common in conveyor belts to provide one or more V-guide cleats on the underside of the belt. The V-guide cleats run longitudinally along the entire length of the underside of the belt and are used to maintain alignment of the belt during the translational and rotational movements of its operation. Since the cleats on the topside of the belt run in a transverse direction, perpendicular to the V-guides, heretofore separate machines were required for attaching longitudinal V-guides and transverse cleats.
In addition to the large cost of maintaining separate machines to perform these two operations, this procedure has been found to be undesirable in that considerable production time is lost in transporting materials from one machine to the next. Therefore, there is a need for a single machine which can attach cleats both longitudinally, along the length of the belt, as well as transversely, across the width of the belt, with minimal tooling and equipment changeover.
Current machines used for attaching cleats have been found to suffer from numerous shortcomings in several other aspects as well. Most principally, current machines employ a chain drive to move the wheel, which presses the cleats and belt together, across the width of the belt and back again.
This arrangement causes non-uniform pressure exerted by the wheel as it traverses from one lateral side of the belt to the other. This uneven pressure across the width of the belt results in non-uniform adhesion of the cleats across the belt. Thus, there is a need for machines capable of exerting a constant force on the wheel between lateral sides of the belt, regardless of the position of the wheel therebetween.
Furthermore, since current machines employ a chain drive for the return stroke as well as the initial pressing stroke, the return stroke has been found to be undesirably slow, as limited by the speed of the chain drive. While a two-speed motor drive could be provided, such a drive adds to the machine cost. Current production speed of attaching many cleats to a belt is limited by the slow return movement of the carriage after attaching each cleat. Therefore, there is a need to provide machines with a more rapid return stroke of the wheel.
Another shortcoming of current cleat attachment machines is that the force or pressure exerted by the wheel on the cleat is dictated solely by the mass of the wheel, and the gravitational force thereof. There is no means for varying this force. In practice, a wide variety of materials are utilized for both cleats and belts. Some of these materials require greater clamping pressure to adhere securely to each other, and some require less pressure. Also, cleats come in a wide variety of sizes and shapes for use in particular applications. These varying cleats require varying pressures to assure their adherence to the conveyor belt. Therefore, there is a need to provide machines in which the force exerted by the wheel can be varied.
An additional shortcoming of current cleat attachment machines is their inability to accommodate "scooped" or angled cleats without warping or reducing the strength of the cleats. Scooped cleats consist of a generally flat, horizontal base and an oblique stem extending therefrom. Currently, in order to attach such scooped cleats, the entire cleat is heated to a temperature sufficient to permit its deformation. The cleat is subsequently passed through a straightening component which flexes the stem of the cleat until it is perpendicular with the base. The cleat is then immediately fed beneath the rolling wheel and passes therethrough in its straightened position. After leaving the wheel, the base now fused to the belt, the stem is left to naturally return to its angled position.
Such means for attaching scooped cleats results in undesirable strain and warping of the cleats due to the flexing thereof, and strain and warping stresses at the fused area. Therefore, there is a need for machines capable of attaching scooped cleats having a variety of angles between the base and stem to conveyor belts, without deforming the cleat in the process.
Lastly, as discussed above, in practice it is common to have cleats and belts of different material being attached in each batch run, with each material having a different melting point. Thus, to obtain optimal fusion between the cleats and belts, different heat requirements are desired for the cleats than for the belts, with different amounts of heat for each individual material being utilized as well. Current machines require extensive tooling and time-consuming adjustments in order to vary the heat imparted to the cleats and belts. Therefore, there is a need for a machine in which the heat imparted to the cleats and belts can be varied simply and quickly.